Avoid the use of Map Reduce because my queued is becoming jam, If I have a

UserEvent

on a Sales Order and I want to take all Items, send JSON to a Suitelet to process(do something else) I don't need the suitelet finish to continue loading/saving my Sales Order because that suitelet would not be writing anything back to the SO... which mean I don't want the user waiting for a background process to finish to continue...

You can start an asynchronous workflow using N/task. The workflow can execute whatever code you want to run via a workflow action script.

I don't see action script...